Tube pump

ABSTRACT

A tube pump includes a base, a columnar inner peripheral surface, a tube disposed along the inner peripheral surface, a rotor disposed concentrically with the inner peripheral surface and supported by the base while squeezing the tube between the rotor and the inner peripheral surface, and a drive unit having a drive shaft passing through the base and configured to couple with the rotor, the base having a cylindrical supporting part configured to support the rotor and the drive shaft being inserted in a hollow portion of the supporting part, the tube pump including a bearing configured to rotatably support the rotor, the rotor having a body on which a coupling hole configured to accommodate the supporting part and the bearing is formed and an annular groove extending in a circumferential direction being formed on an inner peripheral surface of the body, the bearing fitting in the annular groove.

CROSS-REFERENCE TO RELATED APPLICATION

This is a Continuation-in-Part of International Application No.PCT/JP2017/010859 filed on Mar. 17, 2017, which claims priority fromJapanese Patent Application No. 2016-055549 filed on Mar. 18, 2016. Theentire disclosures of the prior applications are incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to tube pumps, rotation restrictingparts, shafts and shaft connection structures.

BACKGROUND

Tube pumps which transport liquid inside an elastic tube arranged in acircular arc along an inner peripheral surface of a casing formed in asubstantially columnar surface by making a roller roll along the innerperipheral surface while squeezing the elastic tube between the innerperipheral surface and the roller have been conventionally known.

A conventionally known tube pump includes a rotor and a drive unitconfigured to rotationally drive the rotor. Furthermore, the rotorrotatably supports a plurality of rollers. The tube pump is configuredsuch that, when the rotor is rotationally driven by the drive unit, eachroller rolls along the inner peripheral surface.

SUMMARY

In the above-mentioned tube pump, a restoring force of the tube squeezedby the rollers acts on the rotor in a radial direction of the rotaryshaft. Furthermore, the rotor is supported by being coupled to a driveshaft of the drive unit. Therefore, the restoring force (radial load) ofthe tube acting on the rotor is transmitted to the drive shaft of thedrive unit. There has been a problem that the drive unit fails or aservice life of the drive unit shortens due to this radial load.

Aspects of the present disclosure are advantageous to provide one ormore improved techniques, for a tube pump, which are capable ofsuppressing failure of a drive unit and elongating service life of thedrive unit.

According to aspects of the present disclosure, there is provided a tubepump including a base, a columnar inner peripheral surface disposed atone face side of the base, a tube of which at least a portion isdisposed along the inner peripheral surface, a rotor disposedconcentrically with the inner peripheral surface and rotatably supportedby the base while squeezing the tube between the rotor and the innerperipheral surface, and a drive unit attached on an other face side ofthe base and having a drive shaft passing through the base andconfigured to couple with the rotor. The base has a cylindricalsupporting part protruding to the one face side and configured tosupport the rotor, and the drive shaft is inserted in a hollow portionof the supporting part. The tube pump further includes a bearing put onan outer periphery of the supporting part and configured to rotatablysupport the rotor. The rotor has a substantially cylindrical body onwhich a coupling hole configured to accommodate the supporting part andthe bearing is formed, and an annular groove extending in acircumferential direction is formed on an inner peripheral surface ofthe body. The bearing fits in the annular groove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an appearance diagram of a tube pump according to anembodiment of the present disclosure.

FIG. 2 is an appearance diagram of the tube pump according to theembodiment of the present disclosure.

FIG. 3 is an exploded view of the tube pump according to the embodimentof the present disclosure.

FIG. 4 is a perspective side view of a pump unit according to theembodiment of the present disclosure.

FIG. 5 is an appearance diagram of a cover according to the embodimentof the present disclosure.

FIG. 6 is an exploded view of a rotor according to the embodiment of thepresent disclosure.

FIG. 7 is a side sectional view of a pump unit according to a variationof the embodiment of the present disclosure.

FIG. 8 is an appearance diagram of a drive unit according to thevariation of the embodiment of the present disclosure.

FIG. 9 is an exploded oblique view of the drive unit according to thevariation of the embodiment of the present disclosure.

FIG. 10 is an appearance diagram of a rotation restricting partaccording to the variation of the embodiment of the present disclosure.

FIG. 11 is an appearance diagram of a gear according to the variation ofthe embodiment of the present disclosure.

FIG. 12 is an appearance diagram of a drive unit of a comparativeexample.

FIG. 13 is an exploded oblique view of the drive unit of the comparativeexample.

FIG. 14 is an appearance diagram of a gear of the comparative example.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiment of the present disclosure will be described withreference to the drawings. Tube pumps according to the embodiments ofthe present disclosure which will be described below are a generictransfusion pumps, and are used for transporting liquids in cleaningdevices, food processing devices, various types of analyzinginstruments, medical instruments and chemical devices. Also, the tubepumps according to the embodiment of the present disclosure can be usednot only for transporting liquids but also for transporting gases andother fluids. In the following description, the same or correspondingnumerals are assigned to the same or corresponding components, andredundant descriptions will be herein omitted.

FIG. 1 and FIG. 2 are appearance diagrams of a tube pump 100 accordingto an embodiment of the present disclosure. FIG. 1 is an oblique viewviewed from a front side of the tube pump 100, and FIG. 2 is an obliqueview viewed from a back side of the tube pump 100. FIG. 3 is an explodedoblique view of the tube pump 100. FIG. 4 is a side sectional view of apump unit 120 included in the tube pump 100.

It is noted that, in the following description, a depth direction/frontrear direction of the tube pump 100 (in FIG. 1, a direction from theupper right toward the lower left) will be referred to as an X-axisdirection, a width direction/right-left direction (in FIG. 1, adirection from the bottom toward the top) will be referred to as aY-axis direction, and a height direction/up-down direction (in FIG. 1, adirection from the lower right toward the upper left) will be referredto as a Z-axis direction. It is noted that, although FIGS. 1-2 show thetube pump 100 in a horizontally disposed state (a position in which thewidth direction of the tube pump 100 is oriented in the verticaldirection), the tube pump 100 can also be installed in a normal attitude(an attitude in which the height direction of the tube pump 100 isoriented in the vertical direction) by altering an orientation of a stay180 which will be described later.

As shown in FIG. 1 and FIG. 2, the tube pump 100 includes a pump unit120 being a main unit of a pump mechanism, a drive unit 110 configuredto drive the pump unit 120, and a stay 180 for attaching the tube pump100. The drive unit 110 and the stay 180 are detachably attached to thepump unit 120 with four bolts 112 a.

The pump unit 120 includes a base 130 and a cover 140. A chassis of thepump unit 120 is configured by the base 130 and the cover 140. As shownin FIG. 3, a rotor 150 and a tube 160 are accommodated inside thechassis of the pump unit 120. The tube 160 is formed of an elastomersuch as a synthetic rubber and has a rubber elasticity.

The drive unit 110 includes a motor 111, a driver 118 configured tosupply driving power to the motor 111, and a reduction gear 112configured to amplify torque of the motor 111. By the reduction gear112, a rotary motion of the motor 111 is decelerated and the torque ofthe motor 111 is amplified. A drive shaft 113 being an output shaft ofthe reduction gear 112 is connected the rotor 150, and the torqueamplified by the reduction gear 112 is transmitted to the rotor 150 viathe drive shaft 113.

The stay 180 is a member formed by, for example, processing a metalsheet such as a stainless steel sheet. The stay 180 has a substantiallyrectangular flat plate like main portion 181, a pair of leg portions 182formed by perpendicularly bending the metal sheet backward at both endsof the main portion 181 in a width direction, and a pair of fixingportions 183 formed by bending the metal sheet outward in the widthdirection at a distal end of each leg portion 182. At a substantiallycentral portion of the main portion 181, an opening 181 a through whichthe drive shaft 113 of the drive unit 110 passes and four through holes181 b disposed at regular intervals around the opening 181 a are formed.Through the through holes 181 b, bolts 112 a for attaching the driveunit 110 to the pump unit 120 are inserted. Hereinafter, the opening 181a and the four through holes 181 b will be collectively referred to as aclearance shape.

The clearance shape of the stay 180 has four times rotation symmetryabout a center of the opening 181 a. Therefore, the stay 180 can beattached to the pump unit 120 even if the stay 180 is rotated about thecenter of the opening 181 a by 90 degrees each time. The tube pump 100can be installed in various attitudes by changing an attachingorientation of the stay 180 to the pump unit 120.

The base 130 has a substantially flat plate like main portion 131, and asubstantially flat plate like bottom plate portion 132 protrudingperpendicularly from a lower end portion of the main portion 131 in theX-axis positive direction. On a back surface of the main portion 131,the drive unit 110 and the stay 180 are fixed. Also, a circular throughhole is formed at the center of the main portion 131, and a cylindricalportion 131 a protruding perpendicularly from a rim of the through holeis formed. In the cylindrical portion 131 a, the drive shaft 113 of thedrive unit 110 is inserted from the back side. Furthermore, to thebottom plate portion 132, a pair of U-shaped cutout portions 132 a inwhich tube joints 161, which will be described later, are to be insertedis formed.

On a front surface of the main portion 131, a rib (guide portion 131 b)protruding perpendicularly from the main portion 131 and extending alonga U-shaped outer rim is formed. The guide portion 131 b is disposedalong an inner side face of a side wall 142 of the cover 140, which willbe described later, when the cover 140 is mounted on the base 130.

FIG. 5 is a diagram of the cover 140 viewed from the back side. Thecover 140 has a substantially flat plate like main portion 141, and aside wall 142 protruding substantially perpendicularly from a rim of themain portion 141. The main portion 141 of the cover 140 is disposed inparallel with the main portion 131 of the base 130 with the rotor 150therebetween. The side wall 142 has a semi-cylindrical upper portion 142a, and a pair of lower portions 142 b extending downwardly from bothends of the upper portion 142 a. The pair of lower portions 142 b aresubstantially flat plate shaped portions formed in parallel with eachother. The side wall 142 is not provided at a lower end of the cover 140(between the pair of lower portions 142 b). In other words, to the sidewall 142, a cutout portion 142 n is formed at a lower end portionopposing the upper portion 142 a formed in the semi-cylindrical shape.

At an end portion of the side wall 142 at the back side, a flangeportion 142 c protruding outwardly from the outer periphery of the sidewall 142 (i.e., expanding in diameter) is formed. On an inner peripheryof the flange portion 142 c, a pair of guiding grooves 142 d 1 (FIG. 5)and one guiding groove 142 d 2 (FIG. 4) are formed. The pair of guidinggrooves 142 d 1 are formed at respective left and right lower endportions of the flange portion 142 c. Also, the guiding groove 142 d 2is formed at an upper end portion of the flange portion 142 c.Furthermore, as shown in FIG. 3, at a rim portion of the main portion131 of the base 130, a pair of projections 131 c 1 and one projection131 c 2, protruding circumferentially, are formed. The pair ofprojections 131 c 1 are formed at both end portions of the main portion131 in the left-right direction in forms that extend in the up-downdirection. Also, the projection 131 c 2 is formed at an upper endportion of the main portion 131. When the cover 140 is mounted on thebase 130, the pair of projections 131 c 1 are fitted in the pair ofguiding grooves 142 d 1, respectively. Furthermore, as shown in FIG. 4,the projection 131 c 2 is fitted in the guiding groove 142 c 2. An innerdiameter of the flange portion 142 c at positions where the guidinggrooves 142 d 1, 142 d 2 are not formed is designed to be substantiallythe same as an outer diameter of the main portion 131 of the base 130 atpositions where the projections 131 c 1, 131 c 2 are not formed.Therefore, when the projections 131 c 1, 131 c 2 are fitted inrespective guiding grooves 142 d 1, 142 d 2, an inner side face of theflange portion 142 c and an end face of the main portion 131 contactwith each other.

Furthermore, the tube pump 100 of the present embodiment includes afixing structure 170 for fixing the cover 140 to the base 130. Thefixing structure 170 of the present embodiment is configured with screwholes (female screws) 171 formed on the cover 140, through holes 172formed on the base 130, and bolts 173 for tightening the cover 140 andthe base 130 together. As shown in FIG. 5 with dotted lines, the screwholes 171 are formed at lower end portions of a pair of lower portions142 b of the cover 140. Furthermore, the through holes 172 are formed atpositions that communicate with the screw holes 171 when the cover 140is mounted on the base 130, and penetrate through the base 130 in theup-down direction. The cover 140 is mounted on the base 130 from abovesuch that the projections 131 c 1 are inserted in corresponding guidegrooves 142 d 1. As the bolts 173 inserted in the through holes 172 frombelow are screwed in the screw holes 171, the cover 140 gets fixed tothe base 130. The rotor 150 and the tube 160 are accommodated in aspecial area surrounded by the cover 140 and the base 130.

FIG. 6 is an exploded oblique view of the rotor 150. The rotor 150includes two disk like frames 151 and 152 forming flange portions. On aback surface of the frame 151 disposed on the front side, four bosses151 a and one cylindrical portion 151 b, protruding perpendicularly, areformed. The four bosses 151 a are disposed around a rotary shaft of therotor 150 at regular intervals (i.e., disposed on a columnar surfaceconcentric with the drive shaft 113). On a front surface of the frame152 disposed on the back side, four bosses 152 a and one cylindricalportion 152 b, protruding perpendicularly, are formed. The four bosses152 a are disposed to oppose to the four bosses 151 a in the X-axisdirection. The cylindrical portion 151 b protrudes perpendicularly froma rim of a through hole provided at the center of the frame 151.Similarly, the cylindrical portion 152 b protrudes perpendicularly froma rim of a through hole provided at the center of the frame 152. Outerdiameters of the cylindrical portion 151 b and the cylindrical portion152 b are substantially the same, and opposing end faces are made toabut against each other to form one continuous cylindrical body 153.

An inner diameter of the body 153 of the rotor 150 is larger than anouter diameter of the cylindrical portion 131 a of the base 130, and ahollow portion of the body 153 accommodates the cylindrical portion 131a of the base 130. Also, a pair of annular bearings 154 a, 154 b and acylindrical spacer 155 are disposed between the body 153 and thecylindrical portion 131 a. The bearings 154 a, 154 b and the spacer 155are fitted in annular grooves formed on an inner periphery of the body153. Furthermore, the spacer 155 are disposed between the bearing 154 aand the bearing 154 b. The spacer 155 is used to hold the bearing 154 aand the bearing 154 b with a predetermined gap therebetween in theX-axis direction. To the spacer 155, a screw hole 155 a penetrating in aradial direction of the spacer 155 is formed. A locking screw 155 b isscrewed in the screw hole 155 a, and one end portion of the lockingscrew 155 b protrudes from an outer peripheral surface of the spacer155. On the body 153, a through hole 153 a is formed. The one endportion of the locking screw protruding from the outer peripheralsurface of the spacer 155 is inserted in the through hole 153 a. By thisconfiguration, displacements of the spacer 155 with respect to the body153 of the rotor 150 in an axial direction (X-axis direction, seconddirection) and in a circumferential direction are restricted, andthereby the spacer 155 is fixed to the body 153.

The bearings 154 a and 154 b are sliding bearings. The bearings 154 aand 154 b are not fixed to the body 153 but are held to be freelyrotatable with respect to the body 153. Furthermore, the bearing 154 ais tucked between a level difference 151 d provided to an innerperiphery of the cylindrical portion 151 b and the spacer 155. By thisconfiguration, a displacement of the bearing 154 a in an axial directionof the bearing 154 a (X-axis direction) is restricted. Similarly, thebearing 154 b is tucked between a level difference 152 d provided to aninner periphery of the cylindrical portion 152 b and the spacer 155. Bythis configuration, a displacement of the bearing 154 b in an axialdirection of the bearing 154 b is restricted. In other words, an annulargroove 153 g extending in a circumferential direction and having thelevel difference 151 d and the level difference 152 d are formed on aninner peripheral surface of the body 153, and the pair of bearings 154 aand 154 b and the spacer 155 are fitted in this annular groove.Therefore, the bearing 154 a and 154 b are held such that only theirrotating movements are permitted. As the bearings 154 a and 154 b, aball bearing in which an inner ring is configured to be freely rotatablewith respect to an outer ring may be used. In this case, the outer ringsof the bearings 154 a and 154 b are fixed by, for example, firmlyfitting to the inner peripheral surfaces of the cylindrical portions 151b and 152 b.

The rotor 150 includes a pair of rollers 156 a and a pair of guiderollers 156 b. The rollers 156 a and the guide rollers 156 b arerotatably supported by corresponding pairs of boss 151 a and boss 152 a.The pair of rollers 156 a are disposed while being arranged in a radialdirection of the rotor 150 with the body 153 therebetween. The pair ofguide rollers 156 b are also disposed while being arranged in a radialdirection of the rotor 150 with the body 153 therebetween. The radialdirection the pair of rollers 156 a are arranged and the radialdirection the pair of guide rollers 156 b are arranged are orthogonal toeach other. That is, the rollers 156 a and the guide rollers 156 b arealternately disposed in a rotating direction of the rotor 150 with 90degrees intervals.

A portion of the roller 156 a protrudes to an outer peripheral side withrespect to the frames 151, 152. The roller 156 a has a substantiallycylindrical shape, and the tube 160 is squeezed between an outerperipheral surface of the roller 156 a and an inner peripheral surface142 e of the cover 140. The guide roller 156 b (FIG. 6) has an outerperipheral surface having a shape of a hyperboloid of one sheet which acentral portion in an axial direction of the guide roller 156 b isconstricted such that the guide roller 156 b conforms to a cylindricalouter peripheral surface of the tube 160 in a non-squeezed state. Aposition of the tube 160 in the X-axis direction is kept at a centralportion of the guide roller 156 b in the X-axis direction by the tube160 contacting the outer peripheral surface of the guide roller 156 b.By this configuration, the tube 160 can be prevented from being damagedby being scratched by the main portion 131 of the base 130, the mainportion 141 of the cover 140, the frame 151 or the frame 152.Furthermore, vibrations of the tube 160 with respect to the rotary shaftof the rotor 150 in an axial direction and a radial direction of therotary shaft of the rotor 150 that occurs during operation can also besuppressed. It is noted that the rotor 150 may include four cylindricalrollers 156 a in place of the pair of rollers 156 a and the pair ofguide rollers 156 b.

As shown in FIG. 4, the tube 160 is nipped between the roller 156 a andthe inner peripheral surface 142 e of the side wall 142 of the cover140, and is squeezed so that an inner peripheral surface of the tube 160is crushed. At a squeezed position (collapsed part) of the tube 160, ahollow portion of the tube 160 is closed. As the roller 156 a rollsalong the inner peripheral surface 142 e of the side wall 142, thecollapsed part of the tube 160 moves along with the roller 156 a, andthereby liquid inside the tube 160 moves in a rotating direction of therotor 150 (a turning direction of the roller 156 a).

As shown in FIG. 4 and FIG. 6, a coupling hole 151 e is formed insidethe cylindrical portion 151 b of the frame 151. The rotor 150 and acoupling shaft 157 are coupled by fitting one end of the coupling shaft157 on the front side in the coupling hole 151 e. On an inner peripheralsurface of the coupling hole 151 e, a plurality of protruding portions151 f extending in the X-axis direction are formed at constant intervalsin a circumferential direction. Also, the one end of the coupling shaft157 on the front side is a spline shaft which a plurality of grooves 157a extending in the X-axis direction are formed on an outer peripheralsurface at constant intervals in a circumferential direction. Thecoupling shaft 157 and the coupling hole 151 e are coupled by a splinejoint by fitting the protruding portions 151 f of the coupling hole 151e in respective grooves 157 a of the coupling shaft 157. The couplingshaft 157 is a substantially cylindrical member. In a hollow portion(fitting hole) of the coupling shaft 157, the drive shaft 113 isinserted. On an inner peripheral surface of the coupling shaft 157, agroove 157 b extending in the X-axis direction is formed.

Next, methods for attaching the rotor 150 and the tube 160 to the tubepump 100 will be described. Attachments of the rotor 150 and the tube160 are performed in a state where the cover 140 is detached from thebase 130 and the drive unit 110 is attached to the base 130. In thisstate, the drive shaft 113 is inserted in a hollow portion of thecylindrical portion 131 a of the base 130. As the rotor 150 is attachedto the front side (X-axis positive direction side) of the base 130, thecylindrical portion 131 a of the base 130 gets inserted in the bearings154 a and 154 b of the rotor 150, and the cylindrical portion 131 a andthe bearings 154 a and 154 b slidably fit. By this configuration, therotor 150 is supported rotatably with respect to the base 130.

Also, as the rotor 150 is attached to the base 130, the coupling shaft157 of the rotor 150 couples with the drive shaft 113. Specifically, onan outer peripheral surface of the drive shaft 113 (FIG. 3), a key 114Pextending in the X-axis direction is provided. The drive shaft 113couples with the coupling shaft 157 as the drive shaft 113 is insertedin the coupling shaft 157 and the key 114P of the drive shaft 113 isaccommodated in the groove 157 b of the coupling shaft 157. Furthermore,since the coupling shaft 157 is coupled to the frame 151 of the rotor150, a rotary motion of the drive shaft 113 is transmitted to the rotor150 via the coupling shaft 157.

After the rotor 150 is coupled to the drive shaft 113, the tube 160 isput on an outer periphery of the rotor 150 to form a U shape. As shownin FIG. 3, a pair of tube connectors 161 are attached at both ends ofthe tube 160. On a back surface of each tube connector 161, a guidinggroove 161 a is formed. Each tube connector 161 is inserted to thecutout portion 132 a of the bottom plate portion 132 of the base 130.Each tube connector 161 is held on the base 130 by a rim portion of thecutout portion 132 a of the bottom plate portion 132 of the base 130being inserted in the guiding groove 161 a. By this configuration,displacements of the tube 160 in the up-down direction and theleft-right direction are prevented and thereby the tube 160 is preventedfrom falling off the rotor 150.

After the tube 160 is attached, the cover 140 is attached to the base130. As indicated in FIG. 3 with an arrow A, the cover 140 is attachedto the base 130 from above.

The pump unit 120 has a guiding structure configured to guide the cover140 to a predetermined position with respect to the base 130. Theguiding structure includes a second direction displacement restrictingstructure for restricting displacement of the cover 140 with respect tothe base 130 in the front-rear direction (X-axis direction, seconddirection), and a third direction displacement restricting structure forrestricting displacement of the cover 140 with respect to the base 130in the right-left direction (Y-axis direction, third direction).

In attaching the cover 140 to the base 130, the cover 140 is positionedwith respect to the base 130 in the X-axis direction by making an endface 142 f (FIG. 5) on a back side of the side wall 142 of the cover 140to abut the rim portion (a portion outside the guide portion 131 b) ofthe main portion 131 of the base 130 from the front side. Also, as theprojection 131 c 1 of the base 130 is inserted in the guiding groove 142d 1 of the cover 140, the projection 131 c 1 gets nipped between a pairof opposing side walls of the guiding groove 142 d 1 from both sides inthe second direction (X-axis direction), and therefore displacement ofthe cover 140 with respect to the base 130 in the second direction isrestricted. That is, a set of the projection 131 c 1 of the base 130 andthe guiding groove 142 d 1 of the cover 140 functions as the seconddirection displacement restricting structure.

Also, rattling of the cover 140 within a plane perpendicular to theX-axis direction can be prevented by the inner side face of the flangeportion 142 c of the cover 140 and an end face of the rim portion of themain portion 131 of the base 130 contacting with each other.Specifically, displacement of the cover 140 with respect to the base 130in the third direction (Y-axis direction) is restricted when the mainportion 131 of the U-shaped base 130 is inserted to the flange portion142 c of the U-shaped cover 140. Also, displacement of the cover 140with respect to the base 130 further downward (Z-axis direction, firstdirection) is restricted when the main portion 131 is inserted up to adeepest part of the flange portion 142 c and an upper end face of thebase 130 contacts an upper end portion of an inner peripheral surface ofthe flange portion 142 c. That is, a set of the flange portion 142 c ofthe cover 140 and the main portion 131 of the base 130 functions as thethird direction displacement restricting structure and the firstdirection displacement restricting structure.

Also, in attaching the cover 140 to the base 130, the cover 140 isguided and positioned to be mounted at a predetermined position in twodirections perpendicular to the rotary shaft of the rotor 150 (Y-axisdirection and Z-axis direction) by the inner side face of the side wall142 of the cover 140 and an outer side face of the guide portion 131 bof the base 130 contacting with each other. That is, a set of the sidewall 142 of the cover 140 and the guide portion 131 b of the base 130functions as the third direction displacement restricting structure andthe first direction displacement restricting structure too.

Also, while attaching the cover 140 to the base 130, the rotor 150 andthe tube 160 enters in the cover 140 from below. A width in theright-left direction of the cutout portion 142 n formed at the lower endportion of the cover 140 is set larger than an outer diameter of therotor 150. Also, the width of the cutout portion 142 n is set to a sizewhich the rotor 150 and the tube 160 put on the outer periphery of therotor 150 can pass through. Therefore, the cover 140 can be attached tothe base 130 from above while accommodating the rotor 150 inside thecover 140 through the cutout portion 142 n. Furthermore, when mountingthe cover 140 to the base 130, the tube 160 gets nipped between therollers 156 a of the rotor 150 and the inner peripheral surface 142 e ofthe cover 140. After being nipped between the rollers 156 a and theinner peripheral surface 142 e, the tube 160 enters in the cover 140while being squeezed.

After the cover 140 is disposed at the predetermined position withrespect to the base 130 while accommodating the rotor 150 and the tube160 therein, the cover 140 and the base 130 are fixed to each other bytwo bolts 173. It is noted that, since the screw holes 171 extend in theup-down direction (cover mounting direction; first direction), the cover140 and the base 130 are tightened together in the up-down direction bythe bolts 173. Therefore, even if an upward force is acting on the cover140 due to the restoring force of the squeezed tube 160, the cover 140can be displaced to the predetermined position while resisting to therestoring force of the tube 160 by tightening forces of the bolts 173acting downward and can be firmly fixed to the base 130. On the otherhand, the only actions needed to remove the cover 140 from the base 130is removing the two bolts 173 and pulling the cover upward.

As described above, in the present embodiment, the rotor 150 and thetube 160 are accommodated inside the cover 140 by mounting the cover 140to the base 130 from above in the state where the rotor 150 and the tube160 are mounted on the base 130. Furthermore, while mounting the cover140, the tube 160 receives a downward force from the cover 140 but doesnot receive forces in the front-rear directions. Therefore, the tube 160is prevented from displacing in an axial direction of the rotor 150 andfalling off the rotor 150 while mounting the cover 140.

Also, after the cover 140 is mounted on the base 130, the position ofthe cover 140 is fixed by the fixing structure 170 (screw holes 171,through holes 172 and bolts 173). Therefore, the cover 140 will notdisplace from the predetermined position with respect to the base 130 byexternal forces or the force from the tube 160.

Also, in the present embodiment, the tube 160 is held on the base 130 byattaching the tube connector 161 of the tube 160 to the cutout portion132 a of the base 130. In this state, displacements of the tube 160 inthe up-down direction and the right-left direction are restricted by theguiding groove 161 a of the holder 161 fitting to the rim portion of thecutout portion 132 a of the bottom plate portion 132, and thereby thetube 160 is prevented from falling off the rotor 150. Furthermore, sincethe tube 160 is held on the base 130 even in a state where the cover 140is not attached to the base 130, there is no need to hold the tube 160to place the tube 160 at an appropriate position while attaching thecover 140 to the base 130. Additionally, since the tube 160 gets nippedbetween the rollers 156 a of the rotor 150 and the inner peripheralsurface 142 e of the cover 140 and then enters in the cover 140 whilebeing squeezed, there is no need to keep the tube 160 in a squeezedstate while attaching the cover 140 to the base 130. Therefore, the tubepump 100 is easy to assemble.

it is noted that a conventionally known tube pump has a base and acover, and a tube and a rotor are accommodated inside the cover. Therotor has a plurality of rollers, and gaps between the rollers and aninner peripheral surface of the cover are set to be narrow such that thetube can be squeezed. Also, a drive unit is mounted on a side of thebase opposite to the cover, and a drive shaft of the drive unit iscoupled to the rotor. The cover is detachable from and attachable to thebase, thereby making it possible to easily perform maintenances of thetube and the rotor.

However, in such known tube pump, the cover covers the rotor aroundwhich the tube is wound from a direction of the rotary shaft and ismounted on the base. Therefore, there has been a problem that, whilemounting the cover on the base, the tube gets pressed by the cover inthe direction of the rotary shaft and drops off the rotor, therebymaking it difficult to properly place the tube between the rotor and theinner peripheral surface of the cover.

Therefore, aspects of the present disclosure are advantageous to provideone or more improved techniques, for a tube pump, which provide a tubepump which can be assembled easily.

Also, in the present embodiment, the rotor 150 is rotatably supported onthe base 130 by the bearings 154 a and 154 b fitting in the cylindricalportion 131 a of the base 130. Furthermore, the drive unit 110 transmitsthe rotary motion to the rotor 150 supported on the base 130 via thedrive shaft 113. By providing the structure for supporting the rotor 150and the structure for transmitting the rotary motion to the rotor 150separately as described above, loads acting on the drive unit 110 can besuppressed.

Specifically, as the rollers 156 a that the rotor 150 has squeeze thetube 160 between the inner peripheral surface 142 e of the cover 140,the rotor 150 receives forces acting in radially inward directions(radial loads) due to the restoring forces of the tube 160 forrecovering from the squeezed state to the original cylindrical state.Furthermore, since the rollers 156 a turn around the rotary shaft of therotor 150, the radial loads also rotate. For example, if the pair ofrollers 156 a are symmetrically disposed in the right-left directionwith respect to the rotary shaft of the rotor 150 (i.e., the pair ofrollers 156 a are arranged in the Y-axis direction), since every rollers156 a squeezes the tube 160 to about the same degree, two radial loadsthe rotor 150 receives from the tube 160 will be cancelled. On the otherhand, if one of the pair of rollers 156 a is positioned above the rotaryshaft and the other is positioned below the rotary shaft, since the pumpunit 120 has a vertically asymmetrical shape (specifically, no side wall142 is formed on the lower half), the radial loads acting on the rotor150 will not be cancelled and thus remain. Furthermore, the radial loadsthat are not cancelled and remained vary in magnitudes and directions inaccordance with a rotating position (phase) of the rotor 150. Assumingthat the varying radial loads act on the drive shaft 113, the drive unit110 may fail or a service life of the drive unit 110 may be shortened.

However, in the present embodiment, the radial loads acting on the rotor150 act on the base 130 via the bearings 154 a, 154 b and thecylindrical portion 131 a on which the bearings 154 a and 154 b are put.Accordingly, the radial loads do not act on the drive shaft 113 andtherefore occurrence of problems such as the failure of the drive unit110 can be suppressed.

(Variation)

Next, a variation of the above-described embodiment will be described.This variation is a tube pump in which the drive shaft 113 of a driveunit 110A and a rotor 150A are coupled via a rotation restricting part114 and a gear 115, which will be described later, in place of thecoupling shaft 157 of the above-described embodiment.

FIG. 7 is a side sectional view of a pump unit 120A of the presentvariation. FIG. 8 and FIG. 9 are an appearance diagram and an explodedoblique view of the drive unit 110A of the present variation,respectively.

As shown in FIG. 8 and FIG. 9, at a distal end of the drive shaft 113 ofthe drive unit 110A, the rotation restricting part 114 and the gear 115are attached by a bolt 116.

FIG. 10 is an appearance diagram of the rotation restricting part 114(an oblique view viewed from the front). The rotation restricting part114 is a member formed by, for example, processing a metal sheet such asa stainless steel sheet. The rotation restricting part 114 has asubstantially disk-shaped base portion 114 b to which a through hole 114c is formed at a central portion, and a substantially strip-shaped(rectangular plate-shaped) leg portion 114 a extending from one end ofthe base portion 114 b.

The substantially disk-shaped base portion 114 b has a substantially Dshape formed by cutting the disk shape with a plane perpendicular to aplate face of the disk shape (D-cut) at a position away from the throughhole 114 c.

The leg portion 114 a protrudes from a central portion of the D-cut endface of the base portion 114 b, is bent at right angles and then extendsin a direction perpendicular to the plate surface of the base portion114 b. As shown in FIG. 8, the leg portion 114 a fits in a key groove113 a (FIG. 9) formed on the drive shaft 113 and restricts rotation ofthe rotation restricting part 114 with respect to the drive shaft 113about a rotation center axis of the drive shaft 113.

Also, to the base portion 114 b, a columnar protruding portion 114 dprotruding in a direction opposite to the direction the leg portion 114a extends is formed. The protruding portion 114 d is formed, forexample, by a half punch press (or a half piercing) process.

FIG. 11 is an appearance diagram of the gear 115 (an oblique view viewedfrom the back). To the gear 115, a through hole 115 c is formedconcentrically with a rotation center axis of the gear 115. Also, on aback surface of the gear 115, a columnar depressed portion 115 d isformed. The protruding portion 114 d formed to the base portion 114 b ofthe rotation restricting part 114 fits in the depressed portion 115 dand restricts rotation of the gear 115 about the rotation center axiswith respect to the rotation restricting part 114. That is, by thefitting of the leg portion 114 a of the rotation restricting part 114 inthe key groove 113 a of the drive shaft 113 and the fitting of theprotruding portion 114 d of the rotation restricting part 114 in thedepressed portion 115 d of the gear 115, the rotation of the gear 115about the rotation center axis with respect to the drive shaft 113 isrestricted, and thereby the gear 115 always rotates integrally with thedrive shaft 113.

The gear 115 and the rotation restricting part 114 are fixed to thedrive shaft 113 by inserting an axis of the bolt 116 in the through hole115 c of the gear 115 and the through hole 114 c of the rotationrestricting part 114 and then screwing the axis of the bolt 116 in ascrew hole (female screw) 113 c formed at a distal end portion of thedrive shaft 113.

Comparative Example

Hereinafter, a comparative example will be used to explain effects thatcan be obtained from the configuration of the above-described variation.FIG. 12 and FIG. 13 are an appearance diagram and an exploded obliqueview of a drive unit 110P being a comparative example, respectively.FIG. 14 is an appearance diagram (oblique view viewed from the back) ofa gear 115P of the comparative example. This comparative example is ageneral configuration example which connects a gear to a drive shaft byusing a key.

The gear 115P has a tubular portion 115Pf on which no tooth 115Pe (FIG.14) is formed. To this tubular portion 115Pf, a hole 115Ph to which thedrive shaft 113 is to be inserted is formed. On a peripheral surface ofthe hole 115Ph, a key groove 115Pd, having the same groove width as thekey groove 113 a of the drive shaft 113, is formed. Rotation of the gear115P with respect to the drive shaft 113 is restricted by fitting a key114P (FIG. 13) both in the key groove 113 a of the drive shaft 113 andthe key groove 115Pd of the gear 115P, and thereby the gear 115P alwaysrotates integrally with the drive shaft 113. Also, to the tubularportion 115Pf, a screw hole (female screw) 115Pg extending in a radialdirection is formed. The drive shaft 113, the key 114P and the gear 115Pare integrated by screwing a locking screw 117P (FIG. 13) into the screwhole 115Pg in a state where the key 114P and the drive shaft 113 areinserted in the hole 115Ph and firmly tightening the key 114P and thedrive shaft 113 together. Further, the gear 115P is securely fixed tothe drive shaft 113 by screwing the bolt 116 in the screw hole 113 cformed at the distal end portion of the drive shaft 113 via the throughhole 115Pc of the gear 115P.

(Comparison Between Variation and Comparative Example)

When the above-described variation and comparative example are compared,since the comparative example has the configuration in which the driveshaft 113 (and the key 114P) fits in the hole 115Ph (and the key groove115Pd) of the gear 115P, an outer diameter of the gear 115P is largerthan an outer diameter of the drive shaft 113. In contrast, in thevariation, since there is no need to insert the drive shaft 113 and thekey 114P into the gear 115, it is possible to make a diameter of thegear 115 smaller than that in the comparative example (e.g., up to adiameter substantially equal to or smaller than that of the drive shaft113).

Also, in the variation, since there is no need to insert the drive shaft113 and the key 114P into the gear 115, there is no need to provide thetubular portion 115Pf. As a result, it becomes possible to make anoverall length of the gear 115 shorter than that of the comparativeexample.

Also, in the comparative example, it is necessary to provide the keygroove 115Pd that engages with the key 114P, but since processing of thekey groove 115Pd being an inner groove is complicated, processing costis relatively high. In contrast, in the variation, the rotationrestriction of the gear 115 is realized by the engagement of thedepressed portion 115 d and the protruding portion 114 d which are easyto process. Furthermore, the rotation restricting part 114 can bemanufactured inexpensively by sheet metal processing.

As described above, according to the configuration of theabove-described variation, it becomes possible to downsize the gear andto attach the gear to the drive shaft with lower cost as compared to thecomparative example. That is, aspects of the present disclosure providesa shaft connection structure which does not need to provide an innergroove having relatively high processing cost and which is easy toreduce its diameter.

It is noted that the coupling shaft 157 of the above-describedembodiment is a member that corresponds to the gear 115P of thecomparative example. That is, in the variation, by the adoption of thegear 115 and the rotation restricting part 114 in place of the couplingshaft 157, it is made possible to downsize the gear 115, while at thesame time eliminate the need of the coupling shaft 157 which has arelatively high processing cost, and thereby cost reduction is realized.It is noted that, in the variation, the gear 115 is downsized but thedrive shaft 113 is thickened to strengthen torsional rigidity of thedrive shaft 113.

The above description is directed to the embodiment of the presentdisclosure. However, the present disclosure is not limited to theconfigurations of the above-described embodiment, but are capable ofvarious modifications within the scope of the technical concept. Forexample, appropriate combinations of at least a part of one or moretechnical configurations of the embodiment explicitly illustrated inthis specification and well-known technical configurations may be alsoincluded in the embodiment of this disclosure.

For example, in the above-described embodiment, the coupling hole 151 eof the rotor 150 and the drive shaft 113 of the drive unit 110 arecoupled by the coupling shaft 157, but the present disclosure is notlimited to this configuration. For example, in place of using thecoupling shaft 157, the drive shaft 113 may be directly coupled to thecoupling hole 151 e. In this case, for example, spline grooves that fitto the protruding portions 151 f of the coupling hole 151 e are formedon the distal end portion of the drive shaft 113. Alternatively, theframe 152 and the coupling shaft 157 may be integrally formed.

In the above-described embodiment, a portion of the roller 156 aprotrudes to an outer peripheral side with respect to the frames 151,152, but the present disclosure is not limited to this configuration.The entire roller 156 a may be disposed slightly to an inner peripheralside with respect to outer peripheral edges of the frames 151, 152.

In the above-described embodiment, the rotor 150 configured to rotatablysupport a plurality of rollers, but the present disclosure is notlimited to this configuration. For example, a configuration in which aroller having an eccentric rotary shaft is used in place of the rotor150 is also within the scope of the present disclosure.

In the above-described embodiment, the screw holes 171, the throughholes 172 and the bolts 173 are used as the fixing structure 170 forfixing the cover 140 to the base 130 and the cover 140 is screwed to thebase 130, but the present disclosure is not limited to thisconfiguration. It is sufficient that the fixing structure 170 can beswitched between a fixed state in which the displacement of the cover140 with respect to the base 130 in the up-down direction is restrictedand a state where the fixing is released, and the method therefor is notlimited to screwing.

In the above-described embodiment, resins are used as materials for themain structural members of the tube pump 100 (e.g., the base 130, thecover 140 and the rotor 150), but other types of structure materialssuch as aluminum alloys or magnesium alloys may be used.

In the above-described variation, the through hole 114 c for insertingthe bolt 116 is formed to the rotation restricting part 114, but acutout or a groove hole having an open end may be provided in place ofthe through hole 114 c.

In the above-described variation, the leg portion 114 a is formed in therectangular plate shape, but the leg portion 114 a having other shapemay be provided. For example, a wedge-shaped leg portion that graduallygets thinner as it approaches a distal end, like a sloping key, may beprovided.

In the above-described variation, the protruding portion 114 d isprovided to the rotation restricting part 114 and the depressed portion115 d is provided to the gear 115. However, conversely, the depressedportion may be provided to the rotation restricting part and theprotruding portion may be provided to the gear.

In the above-described variation, one protruding portion 114 d and onedepressed portion 115 d are provided, but a plurality of depressedportions and protruding portions may be provided. In this case, thedepressed portions (protruding portions) may be formed around a rotationcenter axis of the rotation restricting part (or the gear) at constantintervals.

Both the depressed portion and the protruding portion may be provided tothe rotation restricting part and the gear, respectively. Also, in theabove-described embodiment, the protruding portion 114 d and thedepressed portion 115 d are formed in columnar shapes, but they may haveother shapes provided that they are shapes that mutually fit. Forexample, the depressed portion may be a linearly extending key groove(e.g., a rectangular groove, a V-shaped groove or a U-shaped groove),and may be formed in a shape that fits to the protruding portion.

Hereinabove, the illustrative embodiment according to aspects of thepresent disclosure has been described. The present disclosure can bepracticed by employing conventional materials, methodology andequipment. Accordingly, the details of such materials, equipment andmethodology are not set forth herein in detail. In the previousdescriptions, numerous specific details are set forth, such as specificmaterials, structures, chemicals, processes, etc., in order to provide athorough understanding of the present disclosure. However, it should berecognized that the present disclosure can be practiced withoutreapportioning to the details specifically set forth. In otherinstances, well known processing structures have not been described indetail, in order not to unnecessarily obscure the present disclosure.

What is claimed is:
 1. A tube pump, comprising: a base; a columnar innerperipheral surface disposed at one face side of the base; a tube ofwhich at least a portion is disposed along the inner peripheral surface;a rotor disposed concentrically with the inner peripheral surface androtatably supported by the base while squeezing the tube between therotor and the inner peripheral surface; and a drive unit attached on another face side of the base and having a drive shaft passing through thebase and configured to couple with the rotor, wherein the base has acylindrical supporting part protruding to the one face side andconfigured to support the rotor, wherein the drive shaft is inserted ina hollow portion of the supporting part, wherein the tube pump furthercomprises a bearing put on an outer periphery of the supporting part andconfigured to rotatably support the rotor, wherein the rotor has asubstantially cylindrical body on which a coupling hole configured toaccommodate the supporting part and the bearing is formed, wherein anannular groove extending in a circumferential direction is formed on aninner peripheral surface of the body, and wherein the bearing fits inthe annular groove.
 2. The tube pump according to claim 1, wherein thebearing is a sliding bearing rotatably fitted in the annular groove. 3.The tube pump according to claim 1, comprising: a pair of the bearings;and a cylindrical spacer tucked between the pair of bearings and placedon the outer periphery of the supporting part, wherein the pair ofbearings and the spacer fit in the annular groove.
 4. The tube pumpaccording to claim 3, wherein the spacer is fixed to the body of therotor.
 5. The tube pump according to claim 1, comprising a couplingmember configured to couple the drive shaft of the drive unit and therotor, wherein a coupling hole in which one end of the coupling shaftfits is formed at a center of the rotor, and wherein a fitting hole inwhich a distal end of the drive shaft fits is formed on one end of thecoupling member.